1. Field of the Invention
The present invention relates to an electromagnetically operable coupling device for coupling rotatable bodies and a transmission system including such a coupling device.
2. Description of Related Art
In machines where there are first and second rotatable bodies that can be selectively disconnected or connected together to transfer drive between them, actuation of the coupling device is typically achieved using a mechanical switching arrangement for example using a series of interconnected levers and shafts or use of a hydraulic system. For example, a conventional manual dog transmission system as typically used in motor sport may use a gear lever to select a new gear. The gear lever is connected to a shaft that in turn is connected to a fork; The fork moves a dog ring into and out of engagement with gear wheels mounted on a shaft to select between gear ratios. Alternatively, the system may include a hydraulic circuit for actuating the fork or an electro-mechanical system that uses electric motors to move the fork in response to a gear selection made by operating an electrical switch.
A mechanical actuator arrangement is used in the instantaneous transmission system described in PCT/GB2004/001976. In that system, a gear lever is connected to a shaft and two forks are mounted on the shaft. The forks are arranged to actuate a pair of disc springs to operate two engagement bar sets to selectively engage two gear wheels.